CHEMICAL CHANGES Flashcards

1
Q

What is an acid?

A

A substance that forms aqueous solutions with a pH below 7

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2
Q

What ions do acids form in water?

A

H+ ions

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3
Q

What is a base?

A

A substance with a pH above 7 (e.g. an alkali)

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4
Q

What ions do alkalis form in water?

A

OH- ions

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5
Q

What is the reaction between acids and bases called?

A

Neutralisation

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6
Q

What is the word equation for the reaction between acids and bases?

A

Acid + base —> salt + water

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7
Q

What are some examples of bases?

A

Metal oxides
Metal hydroxides
Metal carbonates

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8
Q

What do acids and metal oxides form?

A

Salt and water

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9
Q

What do acids and metal hydroxides form?

A

Salt and water

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10
Q

How do you form the salts name?

A

Metal + acid(ide)

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11
Q

What do acids and metal carbonates form?

A

Salt and water and carbon dioxide

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12
Q

How do you make soluble salts?

A

React an acid and insoluble base

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13
Q

What is the reactivity series?

A

Potassium
Sodium
Lithium
Calcium
Magnesium
CARBON
Zinc
Iron
HYDROGREN
Copper

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14
Q

What does it mean when a metal is reactive?

A

How quickly they can lose electrons to form positive ions

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15
Q

What is formed when an acid and metal react?

A

Salt and hydrogen

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16
Q

What is formed when a metal reacts with water?

A

Metal hydroxide and hydrogen

17
Q

What is oxidation?

A

Gain of oxygen (loss of electrons)

18
Q

What is reduction?

A

Loss of oxygen (gain of electrons)

19
Q

How can metals be extracted from their metal oxides by reduction using carbon?

A

Carbon replaces the metal it is more reactive than in the equation (takes away its oxygen)

20
Q

What is a redox reaction?

A

When oxidation and reduction are happening at the same time

21
Q

What is the rule for displacement reactions?

A

A more reactive metal will displace a less reactive metal from its compound

22
Q

Losing and gaining of electrons shown in an equation?

A

If a metal reacts with something it gains positive ions and loses two electrons so = Fe –> Fe2+ +2E-
If a metal is less reactive it loses positive ions and gains two electrons so
= Cu2 +2E- –> Cu

23
Q

In a displacement reaction, which reactant is being oxidised?

A

The metal

24
Q

In a displacement reaction, which reactant is being reduced?

A

The metal compound

25
Q

What is an electrolyte?

A

A molten or dissolved ionic compound

26
Q

What happens during electrolysis?

A

An electric current is passed through an electrolyte
The ions then move towards this and react causing the compound to decompose

27
Q

What happens to the positive ions in electrolysis?

A

They move towards the negatively charged cathode and gain electrons (they are reduced)

28
Q

What happens to the negative ions in electrolysis?

A

They move towards the positively charged anode and lose electrons (they are oxidised)

29
Q

Why cant an ionic solid be electrolysed?

A

Because the ions are in fixed positions and cant move

30
Q

Why can molten ionic compounds be electrolysed?

A

Because the ions can move freely and conduct electricity

31
Q

What happens during electrolysis of molten ionic solids?

A

Positive metal ions are reduced to the element at the cathode
Negative metal ions are oxidised to the element at the anode

32
Q

How are metals extracted from their ores (metal oxides) using electrolysis? aluminium and oxygen

A

Positive Al3+ ions are attracted to the cathode where they pick up 3 electrons and turn into aluminium atoms
Negative O2- ions are attracted to the anode where they lose 2 electrons and then combine to form oxygen (O2)

33
Q

What ions do non-metals form?

A

Negative ions

34
Q

What ions do metals form?

A

Positive ions

35
Q

In aqueous solutions (during electrolysis) what other ions are present?

A

Hydrogen ions (H+)
Hydroxide ions (OH-)

36
Q

What happens at the cathode during electrolysis in aqueous solutions? H

A

Hydrogen gas will be produced if the metal is more reactive than hydrogen (if not then a solid layer of the pure metal is produced)

37
Q

What happens at the anode during electrolysis in aqueous solutions?

A

If OH- and halide ions are present then molecules of chlorine bromine or iodine will be formed
If not then the OH- ions are discharged and oxygen is formed